Electronic equipment enclosures, whether of the skeletal frame-type or full cabinet-type, are used for housing electronic equipment, telecommunication switching gear, computer servers, and similar electronic devices. There is an ever increasing need for such electronic equipment enclosures to be so-called "earthquake resistant" or "fault tolerant". That is, for many locations, they must be designed to withstand high vibratory stresses in three axes, such as are present in earthquake prone locations, military installations, and similar sites. Such high strength is needed to keep the equipment frames and enclosures from going into harmonic vibration which can lead to self destruction, and to withstand high cantilever lateral loads. An industry standard, known as the so-called Seismic Zone 4 standard (issued as the Bellcore Specification NEBS, GR-63-CORE, Issue 1) has been developed for such enclosures. Successful testing to that standard is used by manufacturers of such earthquake resistant electronic enclosures to claim that are Seismic Zone 4 compliant. Such Seismic 4 testing assures sufficient resistance to torsional loads, lateral loads, vibratory loads, and other severe tremor-created conditions.
One prior attempt to create an earthquake-resistant electronic equipment enclosure is U.S. Pat. No. 5,979,672 (Gemra, et al). That electronic equipment enclosure has a unitized or monocoque-type enclosure formed of one continuous corrugated panel, i.e., with all the side, top, and bottom sections formed of corrugated metal. In effect, the connected (or continuous folded) corrugated panels provide a continuous envelope for the structure. However, there are practical difficulties in trying to economically manufacture such an enclosure. Further, there is no side access permitted with that frame design, plus the fastening and mounting locations for the equipment shelves are severely limited.